[gssapi-openssh.git] / openssh / kexgssc.c

/*
 * Copyright (c) 2001-2005 Simon Wilkinson. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"

#ifdef GSSAPI

#include <openssl/crypto.h>
#include <openssl/bn.h>

#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "kex.h"
#include "log.h"
#include "packet.h"
#include "dh.h"
#include "canohost.h"
#include "ssh2.h"
#include "ssh-gss.h"

void
kexgss_client(Kex *kex) {
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
        gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
	Gssctxt *ctxt;
	OM_uint32 maj_status, min_status, ret_flags;
	u_int klen, kout, slen = 0, hashlen, strlen;
	DH *dh; 
	BIGNUM *dh_server_pub = NULL;
	BIGNUM *shared_secret = NULL;
	BIGNUM *p = NULL;
	BIGNUM *g = NULL;	
	u_char *kbuf, *hash;
	u_char *serverhostkey = NULL;
	char *msg;
	char *lang;
	int type = 0;
	int first = 1;
	int gex = 0;
	int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;

	/* Initialise our GSSAPI world */	
	ssh_gssapi_build_ctx(&ctxt);
	if (ssh_gssapi_id_kex(ctxt, kex->name, &gex) == NULL)
		fatal("Couldn't identify host exchange");

	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
		fatal("Couldn't import hostname");
	
	if (gex) {
		debug("Doing group exchange\n");
		nbits = dh_estimate(kex->we_need * 8);
		packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
		packet_put_int(min);
		packet_put_int(nbits);
		packet_put_int(max);

		packet_send();

		packet_read_expect(SSH2_MSG_KEXGSS_GROUP);

		if ((p = BN_new()) == NULL)
			fatal("BN_new() failed");
		packet_get_bignum2(p);
		if ((g = BN_new()) == NULL)
			fatal("BN_new() failed");
		packet_get_bignum2(g);
		packet_check_eom();

		if (BN_num_bits(p) < min || BN_num_bits(p) > max)
			fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
			    min, BN_num_bits(p), max);

		dh = dh_new_group(g, p);
	} else {
		dh = dh_new_group1();
	}
	
	/* Step 1 - e is dh->pub_key */
	dh_gen_key(dh, kex->we_need * 8);

	/* This is f, we initialise it now to make life easier */
	dh_server_pub = BN_new();
	if (dh_server_pub == NULL)
		fatal("dh_server_pub == NULL");

	token_ptr = GSS_C_NO_BUFFER;
			 
	do {
		debug("Calling gss_init_sec_context");
		
		maj_status = ssh_gssapi_init_ctx(ctxt,
		    kex->gss_deleg_creds, token_ptr, &send_tok,
		    &ret_flags);

		if (GSS_ERROR(maj_status)) {
			if (send_tok.length != 0) {
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
				    send_tok.length);
			}
			fatal("gss_init_context failed");
		}

		/* If we've got an old receive buffer get rid of it */
		if (token_ptr != GSS_C_NO_BUFFER)
			xfree(recv_tok.value);

		if (maj_status == GSS_S_COMPLETE) {
			/* If mutual state flag is not true, kex fails */
			if (!(ret_flags & GSS_C_MUTUAL_FLAG))
				fatal("Mutual authentication failed");

			/* If integ avail flag is not true kex fails */
			if (!(ret_flags & GSS_C_INTEG_FLAG))
				fatal("Integrity check failed");
		}

		/* 
		 * If we have data to send, then the last message that we
		 * received cannot have been a 'complete'. 
		 */
		if (send_tok.length != 0) {
			if (first) {
				packet_start(SSH2_MSG_KEXGSS_INIT);
				packet_put_string(send_tok.value,
				    send_tok.length);
				packet_put_bignum2(dh->pub_key);
				first = 0;
			} else {
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
				    send_tok.length);
			}
			packet_send();
			gss_release_buffer(&min_status, &send_tok);

			/* If we've sent them data, they should reply */
			do {	
				type = packet_read();
				if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
					debug("Received KEXGSS_HOSTKEY");
					if (serverhostkey)
						fatal("Server host key received more than once");
					serverhostkey = 
					    packet_get_string(&slen);
				}
			} while (type == SSH2_MSG_KEXGSS_HOSTKEY);

			switch (type) {
			case SSH2_MSG_KEXGSS_CONTINUE:
				debug("Received GSSAPI_CONTINUE");
				if (maj_status == GSS_S_COMPLETE) 
					fatal("GSSAPI Continue received from server when complete");
				recv_tok.value = packet_get_string(&strlen);
				recv_tok.length = strlen; 
				break;
			case SSH2_MSG_KEXGSS_COMPLETE:
				debug("Received GSSAPI_COMPLETE");
				packet_get_bignum2(dh_server_pub);
				msg_tok.value =  packet_get_string(&strlen);
				msg_tok.length = strlen; 

				/* Is there a token included? */
				if (packet_get_char()) {
					recv_tok.value=
					    packet_get_string(&strlen);
					recv_tok.length = strlen;
					/* If we're already complete - protocol error */
					if (maj_status == GSS_S_COMPLETE)
						packet_disconnect("Protocol error: received token when complete");
					} else {
						/* No token included */
						if (maj_status != GSS_S_COMPLETE)
							packet_disconnect("Protocol error: did not receive final token");
				}
				break;
			case SSH2_MSG_KEXGSS_ERROR:
				debug("Received Error");
				maj_status = packet_get_int();
				min_status = packet_get_int();
				msg = packet_get_string(NULL);
				lang = packet_get_string(NULL);
				fatal("GSSAPI Key Exchange Error: \n%s",msg);
			default:
				packet_disconnect("Protocol error: didn't expect packet type %d",
		    		type);
			}
			token_ptr = &recv_tok;
		} else {
			/* No data, and not complete */
			if (maj_status != GSS_S_COMPLETE)
				fatal("Not complete, and no token output");
		}
	} while (maj_status & GSS_S_CONTINUE_NEEDED);

	/* 
	 * We _must_ have received a COMPLETE message in reply from the 
	 * server, which will have set dh_server_pub and msg_tok 
	 */

	if (type != SSH2_MSG_KEXGSS_COMPLETE)
		fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");

	/* Check f in range [1, p-1] */
	if (!dh_pub_is_valid(dh, dh_server_pub))
		packet_disconnect("bad server public DH value");

	/* compute K=f^x mod p */
	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_server_pub, dh);

	shared_secret = BN_new();
	BN_bin2bn(kbuf,kout, shared_secret);
	memset(kbuf, 0, klen);
	xfree(kbuf);

	if (gex) {
		kexgex_hash(
		    kex->evp_md,
		    kex->client_version_string,
		    kex->server_version_string,
		    buffer_ptr(&kex->my), buffer_len(&kex->my),
		    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
		    serverhostkey, slen,
 		    min, nbits, max,
		    dh->p, dh->g,
		    dh->pub_key,
		    dh_server_pub,
		    shared_secret,
		    &hash, &hashlen
		);
	} else {
		/* The GSS hash is identical to the DH one */
		kex_dh_hash( kex->client_version_string, 
		    kex->server_version_string,
		    buffer_ptr(&kex->my), buffer_len(&kex->my),
		    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
		    serverhostkey, slen, /* server host key */
		    dh->pub_key,	/* e */
		    dh_server_pub,	/* f */
		    shared_secret,	/* K */
		    &hash, &hashlen
		);
        }

	gssbuf.value = hash;
	gssbuf.length = hashlen;

        /* Verify that the hash matches the MIC we just got. */
	if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
		packet_disconnect("Hash's MIC didn't verify");

	xfree(msg_tok.value);

	DH_free(dh);
	if (serverhostkey)
		xfree(serverhostkey);
	BN_clear_free(dh_server_pub);

	/* save session id */
	if (kex->session_id == NULL) {
		kex->session_id_len = hashlen;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	if (gss_kex_context == NULL)
		gss_kex_context = ctxt;
	else
		ssh_gssapi_delete_ctx(&ctxt);

	kex_derive_keys(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}

#endif /* GSSAPI */
Commit	Line	Data
1c14df9e	1	/*
34fee935	2	* Copyright (c) 2001-2005 Simon Wilkinson. All rights reserved.
1c14df9e	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
	26
	27	#ifdef GSSAPI
	28
	29	#include <openssl/crypto.h>
	30	#include <openssl/bn.h>
	31
	32	#include "xmalloc.h"
	33	#include "buffer.h"
	34	#include "bufaux.h"
	35	#include "kex.h"
	36	#include "log.h"
	37	#include "packet.h"
	38	#include "dh.h"
8bb69cbe	39	#include "canohost.h"
1c14df9e	40	#include "ssh2.h"
1c14df9e	41	#include "ssh-gss.h"
1c14df9e	42
1c14df9e	43	void
34fee935	44	kexgss_client(Kex *kex) {
	45	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	46	gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
1c14df9e	47	Gssctxt *ctxt;
1c14df9e	48	OM_uint32 maj_status, min_status, ret_flags;
e00da40d	49	u_int klen, kout, slen = 0, hashlen, strlen;
1c14df9e	50	DH *dh;
34fee935	51	BIGNUM *dh_server_pub = NULL;
	52	BIGNUM *shared_secret = NULL;
	53	BIGNUM *p = NULL;
	54	BIGNUM *g = NULL;
e00da40d	55	u_char kbuf, hash;
e00da40d	56	u_char *serverhostkey = NULL;
88928908	57	char *msg;
88928908	58	char *lang;
1c14df9e	59	int type = 0;
1c14df9e	60	int first = 1;
34fee935	61	int gex = 0;
e00da40d	62	int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
34fee935	63
34fee935	64	/* Initialise our GSSAPI world */
1c14df9e	65	ssh_gssapi_build_ctx(&ctxt);
34fee935	66	if (ssh_gssapi_id_kex(ctxt, kex->name, &gex) == NULL)
1c14df9e	67	fatal("Couldn't identify host exchange");
8bb69cbe	68
34fee935	69	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
	70	fatal("Couldn't import hostname");
	71
	72	if (gex) {
	73	debug("Doing group exchange\n");
	74	nbits = dh_estimate(kex->we_need * 8);
34fee935	75	packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
	76	packet_put_int(min);
	77	packet_put_int(nbits);
	78	packet_put_int(max);
	79
	80	packet_send();
	81
	82	packet_read_expect(SSH2_MSG_KEXGSS_GROUP);
	83
	84	if ((p = BN_new()) == NULL)
	85	fatal("BN_new() failed");
	86	packet_get_bignum2(p);
	87	if ((g = BN_new()) == NULL)
	88	fatal("BN_new() failed");
	89	packet_get_bignum2(g);
	90	packet_check_eom();
	91
	92	if (BN_num_bits(p) < min \|\| BN_num_bits(p) > max)
	93	fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
	94	min, BN_num_bits(p), max);
	95
	96	dh = dh_new_group(g, p);
	97	} else {
	98	dh = dh_new_group1();
1c14df9e	99	}
1c14df9e	100
1c14df9e	101	/* Step 1 - e is dh->pub_key */
1c14df9e	102	dh_gen_key(dh, kex->we_need * 8);
	103
	104	/* This is f, we initialise it now to make life easier */
34fee935	105	dh_server_pub = BN_new();
	106	if (dh_server_pub == NULL)
	107	fatal("dh_server_pub == NULL");
	108
1c14df9e	109	token_ptr = GSS_C_NO_BUFFER;
	110
	111	do {
	112	debug("Calling gss_init_sec_context");
	113
34fee935	114	maj_status = ssh_gssapi_init_ctx(ctxt,
	115	kex->gss_deleg_creds, token_ptr, &send_tok,
	116	&ret_flags);
1c14df9e	117
1c14df9e	118	if (GSS_ERROR(maj_status)) {
34fee935	119	if (send_tok.length != 0) {
88928908	120	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
88928908	121	packet_put_string(send_tok.value,
34fee935	122	send_tok.length);
34fee935	123	}
1c14df9e	124	fatal("gss_init_context failed");
88928908	125	}
1c14df9e	126
	127	/* If we've got an old receive buffer get rid of it */
	128	if (token_ptr != GSS_C_NO_BUFFER)
34fee935	129	xfree(recv_tok.value);
34fee935	130
1c14df9e	131	if (maj_status == GSS_S_COMPLETE) {
1c14df9e	132	/* If mutual state flag is not true, kex fails */
34fee935	133	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
1c14df9e	134	fatal("Mutual authentication failed");
34fee935	135
1c14df9e	136	/* If integ avail flag is not true kex fails */
34fee935	137	if (!(ret_flags & GSS_C_INTEG_FLAG))
1c14df9e	138	fatal("Integrity check failed");
1c14df9e	139	}
34fee935	140
	141	/*
	142	* If we have data to send, then the last message that we
	143	* received cannot have been a 'complete'.
	144	*/
	145	if (send_tok.length != 0) {
1c14df9e	146	if (first) {
	147	packet_start(SSH2_MSG_KEXGSS_INIT);
	148	packet_put_string(send_tok.value,
34fee935	149	send_tok.length);
1c14df9e	150	packet_put_bignum2(dh->pub_key);
34fee935	151	first = 0;
1c14df9e	152	} else {
	153	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
	154	packet_put_string(send_tok.value,
34fee935	155	send_tok.length);
1c14df9e	156	}
1c14df9e	157	packet_send();
34fee935	158	gss_release_buffer(&min_status, &send_tok);
	159
	160	/* If we've sent them data, they should reply */
	161	do {
	162	type = packet_read();
	163	if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
	164	debug("Received KEXGSS_HOSTKEY");
	165	if (serverhostkey)
	166	fatal("Server host key received more than once");
	167	serverhostkey =
	168	packet_get_string(&slen);
	169	}
	170	} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
1c14df9e	171
1c14df9e	172	switch (type) {
1c14df9e	173	case SSH2_MSG_KEXGSS_CONTINUE:
	174	debug("Received GSSAPI_CONTINUE");
	175	if (maj_status == GSS_S_COMPLETE)
	176	fatal("GSSAPI Continue received from server when complete");
34fee935	177	recv_tok.value = packet_get_string(&strlen);
34fee935	178	recv_tok.length = strlen;
1c14df9e	179	break;
	180	case SSH2_MSG_KEXGSS_COMPLETE:
	181	debug("Received GSSAPI_COMPLETE");
34fee935	182	packet_get_bignum2(dh_server_pub);
	183	msg_tok.value = packet_get_string(&strlen);
	184	msg_tok.length = strlen;
1c14df9e	185
	186	/* Is there a token included? */
	187	if (packet_get_char()) {
	188	recv_tok.value=
88928908	189	packet_get_string(&strlen);
34fee935	190	recv_tok.length = strlen;
1c14df9e	191	/* If we're already complete - protocol error */
	192	if (maj_status == GSS_S_COMPLETE)
	193	packet_disconnect("Protocol error: received token when complete");
34fee935	194	} else {
	195	/* No token included */
	196	if (maj_status != GSS_S_COMPLETE)
	197	packet_disconnect("Protocol error: did not receive final token");
1c14df9e	198	}
1c14df9e	199	break;
88928908	200	case SSH2_MSG_KEXGSS_ERROR:
88928908	201	debug("Received Error");
34fee935	202	maj_status = packet_get_int();
	203	min_status = packet_get_int();
	204	msg = packet_get_string(NULL);
	205	lang = packet_get_string(NULL);
70791e56	206	fatal("GSSAPI Key Exchange Error: \n%s",msg);
1c14df9e	207	default:
	208	packet_disconnect("Protocol error: didn't expect packet type %d",
	209	type);
	210	}
34fee935	211	token_ptr = &recv_tok;
88928908	212	} else {
88928908	213	/* No data, and not complete */
34fee935	214	if (maj_status != GSS_S_COMPLETE)
88928908	215	fatal("Not complete, and no token output");
1c14df9e	216	}
34fee935	217	} while (maj_status & GSS_S_CONTINUE_NEEDED);
	218
	219	/*
	220	* We _must_ have received a COMPLETE message in reply from the
	221	* server, which will have set dh_server_pub and msg_tok
	222	*/
	223
	224	if (type != SSH2_MSG_KEXGSS_COMPLETE)
	225	fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
	226
1c14df9e	227	/* Check f in range [1, p-1] */
34fee935	228	if (!dh_pub_is_valid(dh, dh_server_pub))
34fee935	229	packet_disconnect("bad server public DH value");
1c14df9e	230
34fee935	231	/* compute K=f^x mod p */
	232	klen = DH_size(dh);
	233	kbuf = xmalloc(klen);
	234	kout = DH_compute_key(kbuf, dh_server_pub, dh);
	235
	236	shared_secret = BN_new();
	237	BN_bin2bn(kbuf,kout, shared_secret);
	238	memset(kbuf, 0, klen);
	239	xfree(kbuf);
	240
	241	if (gex) {
e00da40d	242	kexgex_hash(
	243	kex->evp_md,
	244	kex->client_version_string,
34fee935	245	kex->server_version_string,
	246	buffer_ptr(&kex->my), buffer_len(&kex->my),
	247	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	248	serverhostkey, slen,
	249	min, nbits, max,
	250	dh->p, dh->g,
	251	dh->pub_key,
	252	dh_server_pub,
e00da40d	253	shared_secret,
e00da40d	254	&hash, &hashlen
34fee935	255	);
	256	} else {
	257	/* The GSS hash is identical to the DH one */
e00da40d	258	kex_dh_hash( kex->client_version_string,
34fee935	259	kex->server_version_string,
	260	buffer_ptr(&kex->my), buffer_len(&kex->my),
	261	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	262	serverhostkey, slen, /* server host key */
	263	dh->pub_key, /* e */
	264	dh_server_pub, /* f */
e00da40d	265	shared_secret, /* K */
e00da40d	266	&hash, &hashlen
34fee935	267	);
1c14df9e	268	}
34fee935	269
34fee935	270	gssbuf.value = hash;
e00da40d	271	gssbuf.length = hashlen;
34fee935	272
	273	/* Verify that the hash matches the MIC we just got. */
	274	if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
	275	packet_disconnect("Hash's MIC didn't verify");
	276
	277	xfree(msg_tok.value);
	278
	279	DH_free(dh);
	280	if (serverhostkey)
	281	xfree(serverhostkey);
	282	BN_clear_free(dh_server_pub);
	283
	284	/* save session id */
	285	if (kex->session_id == NULL) {
e00da40d	286	kex->session_id_len = hashlen;
34fee935	287	kex->session_id = xmalloc(kex->session_id_len);
	288	memcpy(kex->session_id, hash, kex->session_id_len);
	289	}
	290
	291	if (gss_kex_context == NULL)
	292	gss_kex_context = ctxt;
	293	else
	294	ssh_gssapi_delete_ctx(&ctxt);
	295
e00da40d	296	kex_derive_keys(kex, hash, hashlen, shared_secret);
1c14df9e	297	BN_clear_free(shared_secret);
34fee935	298	kex_finish(kex);
1c14df9e	299	}
	300
	301	#endif /* GSSAPI */